Enhanced antibiotic removal by anaerobic co-digestion in an Expanded Granular Sludge Bed (EGSB) reactor treating real pharmaceutical wastewater: From lab-scale to pilot-plant application

Antibiotics are becoming one of the most detected pollutants in water and wastewater, indicating a risk to both the aquatic ecosystem and human health. In this study, a highly biodegradable honey wastewater (HWW) was used as a co-substrate and supplemented in an expanded granular sludge bed (EGSB) reactor to enhance the treatment of real pharmaceutical wastewater containing amoxicillin (AMX) and erythromycin (ERY). The results showed a significant improvement in AMX and ERY removal, increasing from 60 % and 68 % to 78 % and 72 %, respectively, with enhanced reaction rate constants (k) of 0.27 and 0.24. Similarly, COD removal was markedly improved from 83 % to 89 %, while methane yield increased by 42.11 % in anaerobic co-digestion (AcoD) compared to monodigestion. Despite the advantages of HWW, overly high organic loading (2.5 mL/L) resulted in an unstable system, as indicated by the TVFA/alkalinity ratio of 0.87 ± 0.08, due to propionate accumulation. The application in a pilot-scale system demonstrated satisfactory performance, with effluent quality meeting the standards set by local regulations. This study demonstrates the potential of AcoD using highly biodegradable wastewater as a feasible and economical process, with an operational cost of 0.18 USD/m³, which is significantly lower than that of a complex system.